Field of the Invention
The present invention relates to a radiation heating apparatus for heating gas with sunlight, with heat from a combustion furnace, and with exhaust gas or the like so that useful heat may be extracted.
The present invention also relates to a steam electrolyzing apparatus making use of radiation such as solar heat or the like, which is particularly useful in a sunlight-receiving section of a solar heat electric generator, in a working gas heating section of a solar heat-driven Stirling engine, and in a high-temperature heat exchanger of a high-temperature gas-cooled reactor (HTGR).
FIG. 7 shows a sunlight gas heating apparatus in the prior art. In this apparatus, sunlight 01 is received by an absorber plate 02, whereby liquid metal 03 existing on the rear surface of this absorber plate 02 is heated to generate liquid metal vapor 03', and by means of this liquid metal vapor 03', a heat-exchanger 04, through which heating gas is passing, is heated by the transmission of condensation heat. The entire gas heating apparatus is thermally insulated by heat-insulating material 05. It is to be noted that in this figure, reference numeral 06 designates an inlet through which gas to be heated is introduced, and numeral 06' designates an outlet through which the heated gas is discharged.
Also, a steam electrolyzing apparatus such as that shown in FIG. 8 has been known (Japanese Patent Application No. 1989-271238).
In FIG. 8, steam is fed jointly with argon gas serving as carrier gas through a steam inlet pipe 003 into a light receiving section consisting of a porous ceramic member 002 contained in a quartz glass vessel 001. Steam heated up to 1000.degree. C. by focused sunlight 004 in the porous ceramic member 002 is fed into an electrolyzing cell 005 formed of a cylinder of yttria-stabilized zirconia (hereinafter called YSZ). When a D.C. voltage is applied between a negative electrode 007 connected to a hydrogen electrode 006 made of platinum or YSZ cermet of nickel and a positive electrode 009 connected to an oxygen electrode 008 made of platinum or lanthanum type probschite type oxides (LaCoO.sub.3, LaMnO.sub.3, LaCrO.sub.3, etc.) steam is electrolyzed, and hydrogen is produced on the side of the hydrogen electrode 006, while oxygen is produced on the side of the oxygen electrode 008. The produced oxygen is discharged to the outside through an oxygen outlet pipe 011 by the argon gas fed through a carrier gas inlet pipe 010. The electrolyzing cell 005 is covered by a heat-insulating vessel 012 for the purpose of maintaining the temperature within the cell 005 constant and also preventing the dissipation of heat. In addition, in order to maintain the temperature uniform, sometimes a porous ceramic member 013 is provided at the carrier gas inlet pipe 010 and at the oxygen outlet pipe 011. It is to be noted that reference numeral 014 designates a hydrogen outlet pipe extending through the porous ceramic member 002 and the quartz glass vessel 001 for discharging the produced hydrogen jointly with argon gas and residual steam.
The above-described sunlight gas heating apparatus in the prior art shown in FIG. 7 presented the following problems to be resolved. That is, in the above-described apparatus in the prior art, the liquid metal used as a heating medium is troublesome to handle, because the temperature to which the gas is heated is determined by the boiling point of liquid metal, it is difficult to heat the gas to various desired temperatures, and the layout of the apparatus is limited because of the fact that circulation of the liquid metal is effected by gravity.
Also, if the steam electrolyzing apparatus in the prior art shown in FIG. 8 were operated under a pressurized condition, the porous ceramic member would be heated to a high temperature. The mechanical strength of the quartz tube serving as a light receiving section vessel would be degraded because the porous ceramic member contacts the quartz tube. Thus, the apparatus cannot in fact be used under a pressurized condition.